1. Technical Field
The present invention relates to molds, and more particularly to a mold for molding lenses having two concave surfaces.
2. Description of the Related Art
Glass optical articles, such as aspheric lenses, ball-shaped lenses, and prisms, are generally made by a direct press-molding process using a mold The glass optical articles obtained by the direct press-molding method advantageously do not need to undergo further processing, such as a polishing process. Accordingly, the manufacture efficiency is greatly increased.
A typical mold for molding lenses comprises an upper mold core and a lower mold core. The upper mold core generally has a convex or concave molding surface. However, the lower mold core must have a concave molding surface. If the lower mold core has a convex molding surface, a preformed body that is generally gob-shaped or plate-shaped cannot be readily settled on the lower mold core. Therefore, the typical mold for molding lenses only can mold lenses having two convex surfaces or one convex surface and one concave surface. At least two lenses cooperate to obtain the function of one lens having two concave surfaces. Therefore, the structure of an optical system utilizing the cooperating lenses is complex.
What is needed, therefore, is a mold for molding lenses that can form lenses with two concave surfaces.